1. Field of the Invention
This invention relates to a chain saw, and more particularly to a low-vibration and low-noise guide plate assembly for a chain saw, which includes a porous middle plate and two porous side plates that define a guide groove thereamong for running of an endless saw chain.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional chain saw 1 is shown to include a housing 2, a guide plate assembly 3, a driving gear 4, a guide sprocket 5, and a saw chain 6. The guide plate assembly 3 is connected fixedly to the housing 2, and has a middle plate 301 and two side plates 302. The middle plate 301 is sandwiched and fixed between the side plates 302. The outer peripheries of the middle plate 301 and the side plates 302 define a guide groove 303 thereamong for running of the saw chain 6 around the middle plate 301. The driving gear 4 is mounted rotatably on the housing 2. The guide sprocket 5 is mounted rotatably between the side plates 302. The saw chain 6 has a serrated inner peripheral portion 601 trained between the driving gear 4 and the guide sprocket 5, a plurality of aligned pairs of wings 602, and an outer peripheral saw blade unit 603. Each pair of the wings 602 are attached respectively to two opposite sides of the inner peripheral portion 601, and contact the outer peripheries of the side plates 302. As such, when the driving gear 4 rotates, the saw chain 6 runs within the guide groove 303 and around the middle plate 301.
The aforesaid conventional chain saw 1 suffers from the following disadvantages:
(1) There is no vibration-absorbing means associated with the guide plate assembly 3, thereby creating significant vibration of the saw chain 6 during operation that will result in loud noise, difficulty in handling the chain saw 1, and damage to the guide plate assembly 3 and the saw chain 6.
(2) Because the guide plate assembly 3 is relatively heavy, it is difficult to hold the chain saw 1 during operation.
An object of this invention is to provide a guide plate assembly for a chain saw, which has a vibration-absorbing design that can reduce the vibration of a saw chain.
Another object of this invention is to provide a lightweight guide plate assembly for a chain saw.
According to this invention, a guide plate assembly for a chain saw includes a middle plate that is sandwiched and fixed between two side plates so as to define a guide groove among outer peripheries of the middle plate and the side plates. A saw chain can run within the guide groove. The middle plate has a plurality of first holes formed therethrough. Each of the side plates has a plurality of second holes formed therethrough that are aligned and communicated with the first holes in the middle plate. Because the middle plate and the side plates are porous, they can absorb vibration transmitted from the saw chain during operation. Furthermore, the weight of the guide plate assembly is reduced due to the presence of the first and second holes.